环形通道内再淹没过程先驱冷却传热特性研究

骤冷前沿推进是失水事故后再淹没过程中堆芯冷却速率的重要标志，先驱冷却传热对骤冷前沿的推进起到关键作用，对先驱冷却传热特性的研究十分必要。本文通过数值求解二维非稳态导热方程获得先驱冷却传热系数，并基于环形通道内底部再淹没实验数据，分析先驱冷却传热系数受初始壁温、入口温度和入口质量流速等参数的影响规律。研究结果表明，初始壁温对先驱冷却传热系数的影响不显著，先驱冷却传热系数随入口质量流速的增加而明显增加，随与骤冷前沿距离的增加而减小，基于实验数据得到本参数范围内先驱冷却传热关系式。

Precursory Cooling Heat Transfer Characteristic during Reflood Phase in Annular Channel

Precursory cooling heat transfer has a key effect on quench front progressing velocity which is a symbol of core cooling efficiency during reflood phase. Therefore, the study on precursory cooling heat transfer characteristics is important. In the paper, the influences of initial wall temperature, inlet coolant temperature as well as inlet mass flow flux on precursory cooling heat transfer coefficients were investigated based on results of numerical method solving two-dimensional conduction equations and measured data from bottom reflood experiments in an annular channel. It is shown that precursory cooling heat transfer coefficients are independent on initial wall temperature, increase with the inlet mass flow flux, and decrease with the increase of distance from quench front. A heat transfer correlation of precursory cooling is obtained.